The invention relates to a method of producing powder forged metal components which during subsequent processing are separated into at least two individual parts, with each component being pressed of powder as a one-piece preform to a final separated form, being sintered, forged, cooled and then separated into individual parts.
Such a method is employed, for example, if an article is to be produced which is composed of at least two associated individual parts. In particular, these may be individual parts which must fit together precisely. Such a case exists, for example, for a connecting rod having a divided connecting rod head. Such a connecting rod includes a bearing cap portion and a main rod portion, with these two individual parts being connected together by means of connecting rod screws.
A method of the above-mentioned type is known in which the preform is pressed of powder to excess dimensions (Chiaki Tsumuti and Ichiro Nagare, "Application of Powder Forging To Automotive Parts", FIGS. 8 and 12, in Metal Powder Report, Volume 39, No. 11, published November, 1984, by MPR Publishing Services, Ltd, Shrewsbury, Great Britain). The region of a future separation region or plane between two adjacent individual parts is over-dimensioned. After sintering, forging and cooling, the component is separated into a plurality individual parts. This is done by mechanical working in that the individual parts are separated from one another by sawing at the location of a separation region or plane, with each part having a separating face exposed by the sawing. The over-dimension in this region is substantially removed by the sawing. Thereafter it is necessary to mechanically work the separating faces of each pair of adjacent individual parts. This step may have to be followed by working of the separating faces to obtain a precise fit between the components, for example by grinding.
Because of the over-dimensioning in the region of the separating plane, this method requires the use of material which will later be removed during the sawing. The sawing work and the further mechanical finishing work, quite possibly necessitating grinding, involve a considerable amount of time and expenditure. Since the possibility of insufficient mechanical working of some of the finished articles cannot be completely excluded, some rejects may occur. All these drawbacks are particularly grave if mass production is involved.